r//>^ 



014 338 739 2 9 



558 
8 C3 
py 1 



)ME NUTRITIVE PROPERTIES OF NUTS; THEIR 
PROTEINS AND CONTENT OF WATER- 
SOLUBLE VITAMINE 



<> " 3C 1 

pTa. cajori 



(From the Sheffield Laboratory of Physiological Chemistry, Yale 
University, New Haven) 



Reprinted from 

THE JOURNAL OF BIOLOGICAL CHEMISTRY 
Vol. XLIII, No. 2, September, 1920 



Reprinted from The Journal of Biological Chemistry, Vol. XLIII, No. 2, 1920 



SOME NUTRITIVE PROPERTIES OF NUTS; THEIR 
PROTEINS AND CONTENT OF WATER- 
SOLUBLE VITAMINE.* 

By F. a. CAJORI. 

{From the Sheffield Laboratory of Physiological Chemistry, Yale University, 

New Haven.) 

(Received for publication, June 25, 1920.) 

The extensive series of metabolism experiments on fruitarians 
and nutarians in California reported by Jaffa (1901, 1903) indi- 
cated that nuts used as a substantial component of the diet are 
quite thoroughly digested and are of a higher nutritive value 
than is popularly attributed to them. The same conclusion was 
reached by Cajori (1918) through digestion trials of raw and 
heated nuts, nut butters, and nut pastes. In his experiments 
the coefficient of digestibility for nut proteins and carbohydrates 
fell well within the range of the protein coefficient for a mixed 
diet. There was no indication that nuts are especially resistant 
to the digestive functions of the alimentarj^ canal; so that the 
conclusion seemed justified that nuts are valuable foods and, if 
eaten properly and used in the diet with due regard to their 
concentrated make-up, are on a physiological par with common 
staple articles of the diet. A more detailed investigation of the 
nutritive properties of nuts has, however, hitherto been wanting. 

The Nutritive Value of Nut Proteins. 

It is clearly recognized that individual proteins may vary 
greatly in the proportions of the various amino-acids which may 
be obtained from them and that their dietary value depends in 

* The data in this paper are taken from the dissertation presented by 
the writer for the degree of Doctor of Philosophy, Yale University, 1920. 
A part of the expense of the investigation was defrayed by a grant from 
the Russell H. Chittenden Research Fund for Physiological Chemistry. 

583 

THE JOURNAL Of B.OLOi;;CAL CHEMISTRY, VOL. XLIII, NO. 2 



584 Nutritive Properties of Xuts 

large part on the character of this amino-acid yield. An appre- 
ciation of the significance of these nutritive differences is largely 
due to the extended studies of Osborne and Mendel and others, 
who have demonstrated in the case of the albino rat that the 
naturally occurring proteins differ widely in their efficienc}- for 
maintenance or growth. 

With reference to the chemical make-up of the proteins of nuts, Osborne 
and Clapp (1907, 1907-08) have studied the products of acid hydrolysis of 
amandin and excelsin, the principal proteins of the almond and Brazil nut, 
respectively. Osborne and Harris (1903, a, c, d) compared the distribution 
of basic amino-acid nitrogen in the globulins of the almond, Brazil nut, 
black walnut, English walnut, butternut, and filbert, and have shown that 
the Hopkins-Cole test for tryptophane is strongly positive with all these 
proteins. From the investigations of these authors, the black walnut, 
English walnut, and butternut would seem to contain very similar, if not 
identical, globulins as their principal proteins. The name juglansin has 
been given to this globulin of the juglans species of nut. Osborne and 
Harris (1903, b) found the only essential difference between corylin, the 
globulin from the filbert or hazel nut, and juglansin to be a higher content 
of anaide nitrogen in corylin and a difference in the specific rotation of the 
two proteins. Using Van Slyke's newer method for protein analysis, 
Nollau (1915) has analyzed the pecan nut, peanut, black walnut, and hick- 
ory; Johns and his collaborators (1917, 1919, a) applied the same method 
to a study of the globulins of the peanut and coconut. In all these studies, 
the relatively high content of basic amino-acids found and the presence of 
tryptophane suggest that these nuts are likely to be sources of complete 
protein. Speaking of the. peanut, Johns says: "the relative high percent- 
age of lysine in the proteins of the peanut indicates that this seed might 
be used to advantage in supplementing diets deficient in lysine." 

This conclusion, based on chemical analysis, that nut proteins are of a 
high biological value, has been verified by the feeding experiments of 
Johns and coworkers (1919, h) with the coconut, and Daniels and Loughlin 
(1918) with the peanut. These investigators observed normal growth in 
young rats on diets in which the coconut and peanut furnished the sole 
source of protein. Osborne and Mendel (1912) have maintained rats over 
long periods in which the protein of the dietarj' was derived from excelsin 
of the Brazil nut. 

Feeding Experiments with Rats. 

The experience of numerous investigators in experiments 
involving growth and maintenance has demonstrated the many 
advantages in the use of the rat as an experimental animal in 
nutrition studies. 



Gift 
University 
^OV ; i 1820 



F. A. Cajori 585 

Following the general technique of Osborne and Mendel, 
as recently described by Ferry (1920), we have extended the 
feeding observations on nuts to include the almond, English 
walnut, filbert, pecan, and pine nut. Young rats were fed on 
diets complete in respect to every known dietar}^ essential for 
growth, provided the proteins were of a character to support 
growth. Nut proteins made up approximately 18 per cent of 
the diets. It is well recognized that rats will grow to adult size 
at a normal rate on this level of protein intake, if the protein is 
"complete" from a nutritive point of view; i.e., furnishes all the 
essential amino-acids in suitable amounts. 

There are not many nuts that contain over 3 per cent of nitro- 
gen. Therefore in order to prepare a diet containing 18 per cent 
of protein {e.g. 2,9 per cent N X 6.25) and still insure, in addition 
to the protein, the presence of adequate quantities of the recog- 
nized dietary essentials, fat-soluble and water-soluble vitamines 
and inorganic salts, concentration of the protein of certain of 
the nuts was necessa^3^ To effect this, the shelled nuts were 
passed through a meat grinder and then subjected to pressure in 
a tincture press. This process removed considerable quantities 
of oil from the nut, and nitrogen determinations of the residual 
press cake indicated that the protein content had been sufficiently 
increased to incorporate in the diet at the desired 18 per cent 
protein level. 

Charts 1 and 2 show the growth curves of albino rats on diets 
in which the essential source of protein was derived from nuts. 
At the time these experiments were inaugurated the presence of 
water-soluble vitamine in the nuts used had not been demon- 
strated. Dried brewer's yeast was added to the diets, to the 
extent of 2 per cent, to make sure that they contained adequate 
c}uantities of tliis dietary essential. The possibility of the sup- 
plementary action of the yeast in these diets must be recognized. 
Osborne and IVIendel (1919, a) found yeast to be adequate for 
growth when fed as the sole source of protein. However, the 
amount of protein derived from yeast fed in a concentration of 
2 per cent and its supplementing action cannot be large. In 
Osborne and Mendel's successful experiments the dried yeast 
furnished 30 and 40 per cent of the total food intake. Neuberg 
^lOUV) estimates that 52 per cent of yeast nitrogen is non-protein 



586 



Nutritive Properties of Nuts 



TABLE I. 







Weekly Food Consumption on Nui 


Diets. 








Almond. 


English 
walnut. 


Filbert. 


Pecan. 


Pine 


nut. 


Casein. 


Week. 


Average for Rats 
10, 11. 12. 


Aver- 
age for 
Rats 13, 
14, 15. 


Average for Rats 
16, 17. 


Rat 30. 


Rat 
31 


Rat 
32. 


Rat 
33. 


Rat 7. 


Rats. 




gm. 


gm. 


gm. 


gm. 


gm. 


gm. 


gm. 


gm. 


gm 


1 


45 


50 


40 


43 


40 


39 


42 


41 


41 


2 


41 


40 


40 


60 


40 


45 


42 


44 


42 


3 


33 


42 


39 


48 


35 


39 


38 


53 


48 


4 


42 


47 


44 


46 


34 


35 


44 


50 


52 


5 


44 


51 


44 


47 


41 


53 


50 


54 


54 


6 


50 


45 


41 


47 


33 


44 


37 


61 


59 


7 


55 


50 


54 


44 


40 


48 


43 


59 


57 


8 


49 


50 


41 


43 


41 


44 


48 


61 


63 


9 


51 


48 


58 


44 


40 


53 


57 


63 


54 


10 


53 


48 


45 


55 


59 


57 


52 


54 


47 


11 


51 


48 


54 


52 


50 


59 


46 


61 


58 


12 


51 


46 


56 


52 


51 


53 


55 






13 


50 


47 


45 


54 


47 


45 


50 






14 


52 


42 


38 






46 


52 






15 


56 


43 


53 






45 


45 






16 


66 


43 


53 






48 


55 






17 


57 


41 


50 






54 


50 






18 


48 


38 


41 






63 
65 


62 
66 








Rat 10. 


Rat 12 

+ 
young. 


Rat 16 

+ 
young. 


Rat 17. 




19 


65 


68 


37 


41 




20 


50 


76 




69 


31 






65 


55 






21 


49 


60 




69 


41 






60 


50 






22 


49 


49 




60 


40 






68 


59 






23 


45 


49 




65 


41 






65 


53 






24 


61 


61 




85 


42 






63 


54 






25 


54 


62 




98 








77 


45 






26 




84 




91 








80 








27 




104 




46* 








99 








28 




122 




42 
















29 




117 




















30 




45* 




















31 




44 





















Young removed. 



F. A. Cajori 587 

nitrogen. If this estimation is correct, yeast proteins made up 
but 4 per cent of the total protein of our diets. 

Table I gives the weekly food consumption of the rats on the 
nut diets. The average normal intakes of animals of the same 
weight on a comparable casein diet are on record (Osborne and 
Mendel, 1915). The animals, as a rule, ate less of the nut food 
than did Osborne and Mendel's rats on the casein diet similar in 
composition to that from which their normal intake was calcu- 
lated. The nut foods, consisting of a large quantity of a fat-rich 
press cake probably were of a higher calorific value than the 
casein diet. This fact would explain these differences, as the 
quantity of food eaten by rats which limit their intake to their 
energy requirement is largely determined by the calorific value 
of the food. 

Examination of the growth curves shows that growth resulted 
at a normal rate on all diets except the one in which the pecan 
supplied the protein. The animals on this diet grew at a rate 
about two-thirds normal during the 9 weeks that they were on 
this diet. When casein was introduced into the pecan diet in 
such a waj^ that one-third of the pecan protein was replaced by 
casein, a marked rise in the rate of growth was noted. This 
increased growth may have been due either to a supplementing 
action of the casein or to an increased food intake resulting from 
some favorable modification in the taste or character of the pecan 
diet on addition of casein. 

More experiments are necessary before final conclusions can 
be drawn regarding the comparative efficiency of the proteins 
of the pecan. 

Growth of the second generation of young rats on the nut diets 
is shown in Chart 3. 

With the limited number of observations that we have recorded 
it is not possible to make numerical comparisons of different nut 
proteins, nor were our experiments planned to demonstrate the 
maximum gro\\i:h-promoting power of nut proteins. But, 
accepting the opinion of Osborne and Mendel (1920, a), 
". . . . that if an animal is able to attain adult size upon a 
diet which furnishes protein from a single source, the nutritive 
value of this protein is clearly established," we conclude from our 
experiments that the almond, English walnut, filbert, and pine 
nut are sources of protein adequate for nutrition. 



588 Xutritive Properties of Nuts 

Nuts as Sou7'ces of Water-Soluhle Vitamine. 

Numerous feeding experiments, carried out during the last few 
years, have demonstrated that vitamines are widely distributed 
among plant products. The cereals, vegetables, and forage crops 
have been in^'estigated in some detail as to their content of the 
water-soluble and fat-soluble vitamine. Nuts, as a class, how- 
ever, have received little attention with respect to the presence 
in them of these impoi-tant dietary essentials. 

Halliburton and Drunuiicunl (.1917), studying various naturally occurring 
fats, failed to obtain normal growth in rats when the butter of their diets 
was replaced by coconut oil, peanut oil, or walnut butter. Hence the fat- 
soluble vitamine would seem to be absent in nut oils. Daniels and Loughlin 
(1918) showed that peanuts are lacking in the fat-soluble factor but that 
considerable amounts of the water-soluble vitamine are present; and 
Johns, Finks, and Paul (1919) observed satisfactory growth in young rats 
on diets in which coconut meal was supplemented by butter and inorganic 
salts only and therefore represented the sole source of water-soluble A'ita- 
mine. Mackenzie-Wallis (1918) has reported that a flour made from ground 
peanuts was antiscorbutic. Grieg (1918) used ground nut meal biscuits 
with some success as a therapeutic agent in experimental beri-beri. 

Feeding Experiments with Rats. 

We have studied many of the more common nuts, that have 
not previously received attention, as possible sources of water- 
soluble vitamine and have planned our experiments with a view 
to being able to obtain an approximate quantitative idea of the 
comparative distribution of this essential food factor among 
members of this class of plant products. 

Two methods are available for such trials. An animal may 
be placed on a diet deficient in respect to the water-soluble factor. 
On such a diet, the animal, if it is still small, will cease to grow 
and in any event will, in a short time, begin to decline rapidly in 
weight, a condition that terminates in death unless a change is 
made in the diet. If a product containing sufficient quantities 
of water-soluble vitamine is added to the diet before the animal 
is permanently injured by undernourishment, a rapid recovery of 
weight and nutritive well-being take place. The second method 
depends on the fact that normal growth can be observed in young 
rats only when the product to be tested is available in sufficient 



F. A. Cajori 589 

quantities to supplement an otherwise complete diet with an 
abundance of water-soluble vitamine. 

In the experiments reported below, both methods were em- 
ployed. The basal diet used, consisting of casein, butter fat, 
inorganic salts, starch, and lard, was deficient in water-soluble 
vitamine as evidenced by the rapid decline of animals when 
placed on this food mixture exclusively. Control experiments 
indicated that the casein diet was complete with respect to all 
other food essentials, as normal growth was observed when 
small amounts of brewer's yeast, known to be rich in water- 
soluble vitamine, were added to this diet. 

In the majority of our trials weighed quantities of the nut to 
be tested were fed daily apart from and in addition to the basal 
diet. This method, introduced by Osborne and Mendel (1919, 
h), insures a constant intake of the product under investigation 
and enables a comparison to be made of the potency of the foods 
consumed in like amounts. By varjdng the daily dosage, further 
evidence in respect to the comparative quantities of the water- 
soluble vitamine present can be obtained. 

The nuts were shelled and care was taken to remove all frag- 
ments of the shell and the coarser parts of the integument. In 
the case of the almond, the nut was blanched. The chestnuts 
used in the later trials (Charts 6 and 8) were fed after completely 
freeing them from the adhering integument. We found that the 
rats, at least after the first few days, readily ate the nuts and, as 
a rule, consumed the entire nut allowance as soon as it was placed 
in the cage. The only failure to eat that we experienced was in 
the case of the Brazil nut. It was found necessary to incorporate 
this nut in the basal diet before the animals would consume it in 
the desired amounts. 

The outcome of the restorative trials is shown in Charts 4, 5, 
and 6 and Table II. A daily dosage of 2 gm. of hickory nut, 
pine nut, and pecan, respectively, or the inclusion of 27 per cent 
of almond, or filbert, and 19 per cent of English walnut in the 
food sufficed to enable animals that had declined on the basal 
diet to recover rapidly their nutritional well-being and resume 
growth. 1 g-m. of English walnut, black walnut, hickory nut, 
or pine nut proved to be an equally efficient restorative agent. 
Partial recovery and slow growth resulted from daily consump- 



590 



Nutritive Properties of Nuts 



tion of 1 gm. of almond and 0.5 gm. of chestnut, English walnut, 
or pecan in addition to the basal diet. These charts show that 
all the nuts tested are comparatively rich in water-soluble vita- 
mine. The chestnut, English walnut, and pecan appear to be 
especially potent, daily doses of 0.5 gm. sufficing to permit 
slow growth. The animals receiving 1 gm. daily of either 

TABLE II. 
Weekly Consumption of Basal Diet and Nuts. 





Hickory nut. 


Pine nut. 


Almond. 


\^eek. 


Rat 
4. 


Rat 
6. 


Rat 
38. 


Rat 
39. 


Rat 
8. 


Rat 
9. 


Rat 
34. 


Rat 
35. 


Rat 

2. 


Rat 

18. 


Rat 
19. 


Rat 
20. 




gm. 


gm. 


gm. 


gm. 


gm. 


gm. 


gm. 


gm. 


gm. 


gm. 


gm. 


gm. 


1 


53 


80 


43 


43 


58 


49 


22 


46 


71 


43 


47 


48 


2 


52 


68 


. 32 


37 


55 


45 


13 


37 


63 


41 


41 


26 


3 


42 


65 


49 


29 


56 


44 


31 


53 


55 


43 


39 


39 


4 


59 


58 


61 


36 


45 


37 


74 


78 


32 


45 


48 


46 


5 


49 


61 


62 


58 


31 


29 


78 


60 


65 


25 


38 


29 


6 


80 


101 


63 


55 


46 


32 


73 


55 


72 


27 


27 


22 


7 


62 


82 






79 


58 






69 


44 


42 


41 


8 


62 


78 






59 


58 






71 


43 


49 


36 


9 


58 


73 






60 


63 






59 


43 


51 


40 


10 


68 


78 






60 


58 








30 


40 


40 


11 




















56 


42 


51 


12 




















54 


56 


56 


13 






























Eng 


ish walnut. 






Pecan nut. 




Rats. 


Rat 7. 1 


Rat 24. 


Rat 30. 


Rat 31. 


Rat 21. 


Rat 22. 


Rat 25. 


Rat 26- 




gm. 


i 


im. 


gm. 


on 


I. 




gm. 


gm. 


gm. 


gm. 


gm. 


1 


74 




61 


47 


5 


2 




45 


51 


38 


54 


39 


2 


59 




53 


52 


5 


7 




53 


49 


41 


70 


50 


3 


46 




49 


42 


5 


2 




37 


42 


32 


64 


50 


4 


32 




42 


38 


3 


6 




22 


34 


24 


53 


44 


5 


88 




30 


35 


3 


5 




28 


61 


46 


32 


29 


6 


71 




30 


67 


5 


3 




30 


*59 


42 


23 


24 


7 


55 




23 


68 


5 


7 




31 


45 


31 


47 


40 


8 


55 




60 


61 


5 


8 




48 


58 


37 


50 


49 


9 


67 




57 




5 


3 




57 


54 


35 


54 


42 


10 


77 




73 




5 


9 




63 


60 


35 


44 


44 


11 






59 




7 


3 




51 






52 


62 


12 






53 




5 


3 




48 






59 


69 


13 






















60 


.60 



F. A. Cajori 

TABLE II— Concluded. 



591 







Chestnut. 




Black walnut. 


Filbert. 


Week. 














Rat 27. 


Rat 28. • 


Rat 29. 


Rat 36. 


Rat 37. 


Rat 1. 




gm. 


gm. 


am. 


gm. 


gm. 


gm. 


1 


66 


55 


62 


50 


47 


84 


2 


55 


56 


63 


39 


34 


57 


3 


32 


50 


32 


31 


44 


45 


4 


21 


30 


27 


45 


19 


36 


5 


19 


19 


26 


48 


35 


112 


6 


43 


43 


50 


52 


45 


106 


7 


51 


38 


47 


63 


44 


80 


8 


43 


34 


43 






82 


9 


41 


37 


44 








10 


45 


39 


45 








11 


55 


45 


56 








12 


55 


50 


59 








13 


58 


65 


67 









English walnut or pine nut showed as rapid recovery as in any 
trial where the daily dose of other nuts was 2 gm. A comparison 
of the growth curves indicates that the almond was not so effi- 
cient as a source of water-soluble vitamine. 1 gm. of this nut was 
less effective as a restorative agent than 0.5 gm. of the pecan or 
chestnut. 

Osborne and Mendel (1920, b) beheve that animals which have 
suffered a decline due to a deficiency of water-soluble vitamine 
may become so badly nourished that failure to effect prompt 
resumption of growth may sometimes be ascribed to the condi- 
tion attained by the animal rather than to a lack of the vitamine 
in the tested product used as a supplement to the deficient diet. 
The rats used in our experiments were subjected to quite similar 
degrees of undernutrition and it would seem that the variations 
in rapidity of recovery can be interpreted, in our experiments, as 
being due to differences in the quantity of water-soluble vitamine 
present in different nuts rather than to a radical difference in the 
nutritive condition of the animals at the time that the nut feed- 
ing was inaugurated. The weekly food intakes are shown in 
Table II. 

The growth curves of animals on diets in which nuts, supplied 
in different daily doses, furnished the sole source of water-soluble 



592 



Nutritive Properties of Nuts 



vitamine aie sliown in Charts 7 and 8. Here again, the richness 
of nuts in this vitamine is demonstrated. Normal growth was 
observed when the basal diet was supplemented daily by 2 gm. 

TABLE III. 
W'eekli/ Consumption of Basal Diet and Nuts. 





Almond. 


En 


?lish walnut. 


Brazil nut. 


Black walnut. 




Rat 
18. 


Rat 
19. 


Rat 
20. 


Rat 
21. 


Rat 

22. 


Rat 
23. 


Rat 
24. 


Rat 
25. 


Rat 
26. 


Rat 
34. 


Rat 
35. 




gm. 


gm. 


gm. 


gm. 


gm. 


gm. 


gm. 


gm. 


gm. 


gm. 


gm. 


1 


44 


43 


43 


48 


47 


41 


48 


50 


43 


77 


55 


2 


42 


43 


42 


43 


42 


39 


46 


47 


48 


68 


67 


3 


47 


43 


43 


43 


39 


38 


48 


31 


34 


71 


55 


4 


46 


43 


47 


47 


44 


37 


46 


45 


33 


70 


60 


5 


40 


41 


47 


51 


38 


40 


43 


38 


43 


54 


55 


6 


39 


37 


41 


51 


35 


40 


43 


38 


35 


46 


64 


7 


44 






61 


42 


43 




58 




37 


54 


8 


42 






45 


35 


43 




52 




40 


50 


9 








51 


36 


47 




54 




34 


43 


10 




















31 


62 


11 




















30 


64 




Chestnut. 


Pecan. 


Y 


east. 




Rat 27. 


Rat 28. 


Rat 29. 


Rat 38. 


Rat 39. 


Rat 36. 


Rat 37. 


Rat 9. 




gm. 


gm. 


gm. 


gm. 


gm 




gm. 


gm. 




gm. 


1 


53 


47 


50 


60 


7C 




66 


73 




41 


2 


51 


51 


50 


57 


57 




56 


55 




41 


3 


51 


44 


51 


54 


57 




55 


54 




45 


4 


52 


45 


53 


47 


6S 




48 


66 




47 


5 


51 


52 


68 


52 


61 




52 


62 




43 


6 


42 


45 


45 


60 


61 




54 


55 




39 


7 


60 


53 


57 


55 


5£ 




55 


57 




49 


8 


56 


48 


55 


55 


54 




51 


59 




50 


9 


66 


55 


62 


47 


51 




57 


46 




56 


10 








51 


48 




58 


47 






11 








48 


55 




49 


55 







of the almond, English walnut, chestnut, Brazil nut, or black 
walnut. When the daily ration of the nut was 1 gm,, the pecan 
and chestnut furnished sufficient quantities of this dietarj' factor 
for normal growth. 



F. A. Cajori 593 

The weekly food intakes are shown in Table III. The char- 
acteristic deline in food consumption during the period when 
there was insufficient water-soluble vitamine in the food, and 
the prompt recovery of appetite and resumption of eating when 
the vitamine was added to the diet, are to be noted. 

A^ut Proteins and Milk Production. 

The present experiments with nut diets have furnished an 
opportunity to test some of the relations of the dietaiy proteins 
to milk production, inasmuch as a number of the female rats 
under observation were bred in the course of the feeding trials. 
If the mammarj'' gland has at best a limited power, if any, of 
synthesizing the essential amino-acid precursors of its protein 
complexes (McCollum and Simmonds, 1918), the importance of 
furnishing a proper source of amino-acid groups in the ration 
during lactation is evident. 

In studying the lactation of dairy cows, Hart and Humphrey (1915, 
1916, 1917, 1918), among others have found wide differences in the efficiencies 
of various protein mixtures as producers of milk. Not only the quantitj^ 
but also the biological quality of the proteins in the ration affect the char- 
acter of the mammary secretion. Likewise Hoobler (1917, a, h) has con- 
cluded from studies of Avet nurses that, as a rule, animal proteins are more 
efficient than vegetable proteins for the elaboration of human milk. How- 
ever, nut proteins were an exception to this generalization in that diets 
containing almonds, English walnuts, pecans, and peanut butter as a 
source of protein proved to be as suitable for milk production as diets which 
furnished protein from animal sources. In other words, nuts seemed to 
furnish the nitrogenous complexes necessary for the elaboration of milk as 
effectively as any other type of protein. 

Judging the character of milk production by the ability of 
the mother to nurse her j^oung successfully, we have observed 
satisfactory mammarj' function in rats, on diets containing the 
almond, English walnut, pine nut, and filbert as the essential 
source of protein in the ration. Some loss of weight of the mother 
rat occurred during the nursing period in the experiments with 
the almond, Enghsh walnut, and filbert, but tissue disintegration 
during the temporary decline could scarcely have furnished 
enough indispensable nutrient units to account for the newly 
synthesized milk protein sufficient in quantity to have produced 
the increments in weight observed in all the young. 



594 Nutritive Properties of Nuts 

SUMMARY AND CONCLUSIONS. 

Satisfactory growth was observed in young rats on diets in 
which the almond, English walnut, filbert, and pine nut, respec- 
tively, furnished the essential source of protein in the ration. 

Normal growth can be secured when rats are fed upon other- 
wise adequate diets containing the almond, English walnut, 
black walnut, Brazil nut, chestnut, or pecan as the sole source 
of water-soluble vitamine. Animals which have declined on a 
diet devoid of water-soluble vitamine promptly recover when 
the almond, English walnut, filbert, hickory, pine nut, chestnut, 
or pecan is introduced in the diet. These observations indicate 
that nuts are sources of abundant quantities of water-soluble 
vitamine. 

The proteins of the almond, EngKsh walnut, pine nut or filbert 
furnish the necessary nitrogenous complexes for the elaboration 
of milk in rats. 

I desire to express my hearty thanks to Professor Lafayette 
B. Mendel, Avho suggested this study to me, for his helpful advice 
and criticism during the course of the investigation. 

BIBLIOGRAPHY. 

Cajori, F. A., The utilization of some nuts as food, /. Home Econ., 1918, 

X, 304. 
Daniels, A. L., and Loughlin, R., Feeding experiments with peanuts, J . 

Biol. Chem., 1918, xxxiii, 295. 
Fern', E. L., J. Lab., and Clin. Med., 1920, in press. 
Grieg, E. D. W., Anti-beri-beri vitamine in ground nut meal biscuits, 

Indian J. Med. Research, 1918, vi, 143; abstracted in Chem. Abstr., 

1919, xiii, 2067. 
Halliburton, W. D., and Drummond, J. C, The nutritive value of marga- 
rines and butter substitutes with reference to their content of the 

fat-soluble accessory growth substance, J. Physiol., 1917, li, 235. 
Hart, E. B., and Humphrey, G. C., The relation of the quality of proteins 

to milk production, J. Biol. Chem., 1915, xxi, 239. 
Hart, E. B., and Humphrey, G. C., Further studies of the relation of the 

quality of proteins to milk production, J. Biol. Chem., 1916, xxvi, 457. 
Hart, E. B., and Humphrey, G. C., The relation of the quality of proteins 

to milk production. Ill, J. Biol. Chem., 1917, xxxi, 445. 
Hart, E. B., and Humphrey, G. C., The relation of the quality of proteins 

to milk production. IV, J. Biol. Chem., 1918, xxxv, 367. 



F. A. Cajori 595 

Hoobler, B. R., Problems connected with the collection and production of 

human milk, /. Am. Med. Assn., 1917, (a), Ixix, 421. 
Hoobler, B. R., The effect on human milk production of diets containing 

various forms and quantities of proteins, Am. J. Dis. Child., 1917 (b), 

xiv, 105. 
Jaffa, M. E., Nutritional investigations among fruitarians and Chinese, 

U. S. Dept. Agric, Off. Exp. Stations, Bull. 107, 1901. 
Jaffa, M. E., Further investigations among fruitarians, U. S. Dept. of 

Agric, Off. Exp. Stations, Bull. 132, 1903. 
Johns, C. O., and Jones, D. B., The proteins of the peanut, Arachis hypogea. 

II. The distribution of the basic nitrogen in the globulins arachin and 

conarachin, /. Biol. Chem., 1917, xxx, 33. 
Johns, C. O., Finks, A. J., and Gersdorff, C. E. F., Globulin of the coconut 

(Cocos nucifera). I. Preparation of coconut globulin. Distribution 

of the basic nitrogen in coconut globulin, J. Biol. Chem., 1919 (a), 

xxxvii, 149. 
Johns, C. O., Finks, A. J., and Paul, M. S., Studies in nutrition. I. The 

nutritive value of coconut globulin and coconut press cake, J. Biol. 

Chem., 1919 (6), xxxvii, 497. 
Mackenzie-Wallis, R. L., Food value of the ground nut (Arachis), Indian 

J. Med. Research, 1918, vi, 45; abstracted in Chem. Abstr., 1919, xiii, 

2247. 
McCollum, E. v., and Simmonds, N., The nursing mother as a factor of 

safety in the nutrition of the young. Am. J. Physiol., 1918, xlvi, 275. 
Neuberg, C, cited by Funk, C, Lyle, W. G., and McCaskey, D., J. Biol. 

Chem., 1916, xxvii, 173. 
NoUau, E. H., The amino-acid content of certain commercial feeding- 
stuffs and other sources of protein, J. Biol. Chem., 1915, xxi, 611. 
Osborne, T. B., and Clapp, S. H., Hydrolysis of excelsin. Am. J. Physiol., 

1907, xix, 53. 
Osborne, T. B., and Clapp, S. H., Hydrolysis of amandin from the almond, 

Am. J. Physiol., 1907-08, xx, 471. 
Osborne, T. B., and Harris, I. F., Nitrogen in protein bodies, J. Am. 

Chem. Soc, 1903 (a), xxv, 323. 
Osborne, T. B., and Harris, I. F., The specific rotation of some vegetable 

proteins, J. Am. Chem. Soc, 1903 (6), xxv, 842. 
Osborne, T. B., and Harris, I. F., The globulin of the English walnut, 

American black walnut and the butternut, J. Am. Chem. Soc, 1903 (c), 

xxv, 848. 
Osborne, T. B., and Harris, I. F., The tryptophane reaction of various pro- 
teins, J . Am. Chem. Soc, 1903 (d), xxv, 853. 
Osborne, T. B., and Mendel, L. B., Beobachtungen iiber Wachstum bei 

Fijtterungsversuchen mit isolieten Nahrungssubstanzen, Z. physiol. 

Chem., 1912, Ixxx, 307. 
Osborne, T. B., and Mendel, L. B., The comparative nutritive value of 

certain proteins in growth, and the problem of the protein minimum,. 

J. Biol. Chem., 1915, xx, 351. 



596 Nutritive Properties of Nuts 

Osborne, T. B., and Mendel, L. B., The nutritive value of yeast protein, 

J. Biol. Chem., 1919 (a), xxxviii, 223. 
Osborne, T. B., and Mendel, L. B., Nutritive factors in plant tissues. II. 

The distribution of water-soluble vitamine. Treliminary report, 

./. Biol. Chem., 1919 (6), xxxix, 29. 
Osborne, T. B., and Mendel, L. B., Nutritive value of the proteins of the 

barley, oat, rye, and wheat kernels, J. Biol. Chem., 1920 (a), xli, 275. 
Osborne, T. B., and Mendel, L. B., Nutritive factors in plant tissues. III. 

Further observations on the distribution of water-soluble vitamine, 

J. Biol. Chem., 1920 (6), xli, 451. 



Chart 1. Growth of young rats on diets in which the English walnut, 
pine nut, and pecan, incorporated in the diet in the form of a press cake, 
furnished the essential source of protein. A casein diet of similar com- 
position, except for protein, served as a control experiment. The broken 
line in the curves of Rats 30 and 31 indicate the period when the pecan 
diet was replaced by a mixture of one part casein diet and two parts pecan 
diet. 

The composition of the casein and nut diets was as follows : 

Casein Diet. 

Rat 7. per cent 

Casein 18 

Salt mixture* 4.5 

Starch 50.5 

Butter fat 9 

Lard 18 

Brewer's yeast, dried 200 mg. daily. 

* The salt mixture used in all the diets of the feeding trials is that 
described by Osborne, T. B., and Mendel, L. B., J. Biol. Chem., 1917, 
xxxii, 317. 

English Walnut Diet. 

Rats 13, H, 15. per cent 

English walnut press cake, 3.5 per cent N 82 

Salt mixture 3 

Starch 4 

Butter fat 5 

Lard 4 

Brewer's yeast, dried 2 

Pine Nut Diet. 

Rats Si, SS per cent 

Pine nut 50 

Salt mixture 3 

Starch , 36 

Butter fat 5 

Lard 6 

Brewer's yeast, dried 200 mg. daily. 



F. A. Cajori 



597 




(6 

n 
o 



Pecan Diet. 
Rats so, 31. per cent 

Pecan press cake, 3.6 per cent N 80 

Salt mixture 3 

Starch 7 

Butter fat 5 

Lard 5 

Brewer's yeast, dried 200 mg. daily. 




n 



Chart 2. Growth of young rats on diets where the almond and filbert^ 
incorporated in the diet in the form of a press cake, furnished the essential 
source of protein. 

The composition of the casein diet was the same as given in the descrip- 
tion of Chart 1. The composition of the nut diets was as follows: 

Almond Diet. 
Rats 10, 11, It. percent 

Almond press cake, 5.0 per cent N 58 

Salt mixture 3 

Starch 12 

Butter fat 5 

Lard 20 

Brewer's yeast, dried 2 

598 



F. A. Cajori 



599 



Filbert Diet. 

Rats 16, 17. per cent 

Filbert press cake, 3.6 per cent N 80 

Salt mixture 3 

Starch 3 




Chart 3. Growth of the second generation of young rats on diets in 
which almond, English walnut, filbert, and pine nut, incorporated in the 
diet in the form of a press cake, furnished the essential source of protein. 
The broken line in the curves of Rats 47 and 48 indicates the period when 
the almond diet was replaced by the casein diet and 100 mg. of dried yeast 
daily. 

The composition of the casein and nut diets was the same as described 
in Charts 1 and 2. 



THE JOURNAL OP BIOLOGICAL CHEMISTRY, VOL. XLnl, NO. 2 



600 Nutritive Properties of Nuts 

Chart 4. Recovery of growth of animals which had declined on a diet 
devoid of water-soluble vitamine, on the addition of the almond, filbert, 
hickory nut, pine nut, pecan, and English walnut as supplements to the 
basal diet. 

The animals receiving the hickory nut, pine nut, and pecan were given 
2 gm. of the nut daily. 

The almond, filbert, and English walnut, respectively, were incorpor- 
ated in the diet, one part of nut diet and two parts of basal being thor- 
oughly mixed together. In such a mixture the almond and filbert nut 
furnished 27 per cent of the diet and the English walnut 19 per cent. 

The broken line on the curves denotes the period when the animals were 
on the basal diet. 

The composition of the diets was as follows: 

Basal Diet, 

per cent 

Casein 18 

Salt mixture 4.5 

Starch 50.5 

Butter fat 9 

Lard 18 

Almond Nut Diet. 

Rat t. per cent 

Almond press cake 58 

Salt mixture 3 

Starch 14 

Butter fat 5 

Lard 20 

Filbert Diet. 

Rat 1. per cent 

Filbert press cake 80 

Salt mixture 3 

Starch 5 

Butter fat 5 

Lard 7 

English Walnut Diet. 

Rat S. per cent 

English walnut press cake 82 

Salt mixture 3 

Starch 6 

Butter fat 5 

Lard 4 



F. A. Cajori 



601 



CHART *. 
aROBTH EXPERIMENTS ON RATS. 
RECOTCRY OF OROWTK WITH 'IJTS 
AS SOURCE OF SATER SOLUBLE VITAaiNE 
3.0 Oma. Nut daily 




Chart 4. 



602 



Nutritive Properties of Nuts 




Chart 5. Recovery of growth of animals which had declined on a diet 
devoid of water-soluble vitamine, on the addition of almond, hickory 
nut, black walnut, pine nut, and English walnut as supplements to the 
basal diet. 

The animals were given 1 gm. of nut daily. 

The broken line of the curves denotes the period that the animals were 
on the basal diet. 

The composition of the basal diet was the same as described in Chart 4. 



F. A. Cajori 



603 







CHART 6. 












QROWTH EXFERIilENTS ON RATS. 






' 






RECOVERY OF QROWTH WITH 5UT3 






-^^ 


ISO 




AS SOURCE OF WATER "SOLUbLE VlTArUNE. 














0.5 Oni. 


Vut daily 






y / 




160 




^ 






P 


-'/ / 






140 


• 


s 

X 


\^ 




4f f M 




r 
i 




___, 





V 2i 




Of / 
/ 






J 

/' / 


120 


->,, 


\ 

X 

V 


120 


o 




^\ 




/ ^ 

/y 


o^/*"^^ 


^ 


^1 t 


100 


^' 


«r ^ 




\ 






— y- 
/ 

/ 


120 


^ 


^ 


N 


> 




^ 




/ 






<^ 10 <taye> 




^ X 


A 


Ij^^^ 


^ 




100 






\ 




=Nu 


t replaced ty Yeaat. 



Chart 6. Recovery of growth of animals which had declined on a diet 
devoid of water-soluble vitamine, on the addition of the English walnut, 
chestnut, and pecan as supplements to the basal diet. 

The animals were given 0.5 gm. of nut daily. 

The chestnut was blanched before feeding. 

The broken line indicates the period that the animals were on the 
basal diet alone. 

The composition of the basal diet was the same as described in Chart 4. 



Chart 7. Growth of young rats on diets where the almond, English 
walnut, chestnut, and Brazil nut furnish the sole source of water-soluble 
vitamine. 2 gm. of the nut were fed daily in addition to the basal diet. 
The basal diet was found to be inadequate to support growth unless sup- 
plemented by a source of water-soluble vitamine (see Charts 4, 5, 6). 

The almond was blanched before feeding. The coarser parts of the 
integument of the other nuts were removed. 



604 



Nutritive Properties of Nuts 




The composition of the basal diet was as follows: 

Basal Diet. 



Casein. 



per cent 

. 18 



Salt mixture 4.5 

Starch 50 . 5 

Butter fat 9 

Lard 18 



F. A. Cajori 



605 




Chart 8. Growth of young rats on a diet in which the black walnut, 
Brazil nut, pecan, and chestnut furnish the sole source of water-soluble 
vitamine. 2 gm. of the black walnut and Brazil nut were fed daily in addi- 
tion to the basal ration. 1 gm. of the pecan and chestnut was fed daily 
in addition to the basal ration. 

The chestnut was blanched before feeding. The coarser parts of the 
integument of the other nuts were removed. 



606 Nutritive Properties of Nuts 

The small vertical lines on the growth curves of Rats 25 and 26 indicate 
days when the animals failed to eat any of the nut given in addition to the 
basal ration. The prompt resumption of growth indicates the point 
where the diet was changed to a ration consisting of one part Brazil nut 
diet and two parts basal diet. 

The composition of diets was as follows: 

Basal Diet. 

percent 

Casein 18 

Salt mixture 4.5 

Starch 50.5 

Butter fat 9 

Lard 18 

Brazil Nul Diet, 

Rats S5, £6. per cent 

Brazil nut press cake 80 

Salt mixture 3 

Starch 7 

Butter fat 5 

Lard - ,,,,, 5 



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